In an effort to critically evaluate current strategies for investigational device use in the United States, the New Approaches to Coronary Intervention (NACI) Registry was established in November, 1990. Over a 2 year period, approximately 3000 patients with symptomatic coronary artery disease undergoing revascularization using alternative angioplasty devices will be recruited; an additional 500 patients undergoing standard balloon angioplasty will also be registered. Increasingly, device selection in the NACI Registry is being guided by the presence of certain pre-procedural lesion morphologic characteristics. For the most part, caliper-determined percent diameter stenosis and vessel dimensions before and after the intervention have been used to assess procedural outcome by the clinical site investigator. Recent data, however, suggests that site angiographic readings may be subject to substantial observer variability and potential bias. This potential bias may be compounded by the complex relationship between industry and the investigator. Because of the pivotal importance and profound strategic implications of the NACI Registry, an independent Angiographic Core Laboratory analysis of cineangiograms from the NACI Registry is warranted. Widespread support for independent Angiographic Core Laboratory review has been voiced among the NACI investigators; similar recommendations for new device evaluation were made by the National Heart, Lung, and Blood Institute Workshop on the Evaluation of Emerging Coronary Revascularization Technologies. Detailed, standardized and unbiased qualitative morphologic and quantitative angiographic analysis will be of critical importance for valid device comparison. Based on this proposed analysis, morphologic predictors of success and failure can be determined. Moreover, quantitative analysis using a rapid, computer-assisted edge-detection algorithm allows accurate determination of reference vessel size, minimum lumen diameter, and percent diameter stenosis before and after revascularization. The quantitative contributions of adjunct balloon angioplasty, performed in up to 80% of patients, can also be determined. Central Angiographic Core Laboratory analysis may also provide important quality control feedback to the clinical sites with respect to their angiographic methods. Quality control for the Angiographic Core Laboratory itself will be evaluated and maintained by the NACI Coordinating Center. Adjudication of discrepancies between the clinical sites and Core Laboratory will be performed, seeking to minimize any observer error in the evaluation of the cineangiograms. Our current approach to the use of new devices will evolve markedly based on the findings obtained from the NACI Registry. We believe that the proposed NACI Angiographic Core Laboratory Project will significantly strengthen these conclusions and more definitively shape new device strategies in the coming years.